Semiconductor memory devices, including flash memory, typically utilize memory cells to store data as an electrical value, such as an electrical charge or voltage. A flash memory cell, for example, includes a single transistor with a floating gate that is used to store a charge representative of a data value. Increases in storage density have been facilitated in various ways, including increasing the density of memory cells on a chip enabled by manufacturing developments, and transitioning from single-level flash memory cells to multi-level flash memory cells, so that two or more bits can be stored by each flash memory cell.
A drawback of increasing storage density is that the stored data is increasingly prone to being stored and/or read erroneously. An error control coding (ECC) engine is utilized to limit the number of uncorrectable errors that are introduced by electrical fluctuations, defects in the storage medium, operating conditions, device history, and/or write-read circuitry, etc. Additionally, for many error control codes, the decoding process can be improved by using soft information, which takes into account the associated probabilities of different interpretations of the results of one or more read operations. Hard information decoding generally means that an absolute decision is made as to whether a data value is one value or another. By contrast, soft information includes the probabilities that different interpretations of sensed electrical signals, corresponding to the results of one or more read operations, may be correct. By taking into consideration more information, soft information decoding often improves the error detection and correction capability of a particular error control code, and thus the data storage capacity of a system. However, the utilization of soft information decoding has a number of previously irresolvable drawbacks. For example, soft information decoding implementations tend to introduce undesirable delays (i.e., latencies), have relatively large semiconductor footprints, and are generally power and memory intensive.